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Fwd: Re: floor deflections[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: addseaoc(--nospam--at)euken.com
- Subject: Fwd: Re: floor deflections
- From: rlewis(--nospam--at)techteam.org (Richard Lewis)
- Date: 30 Jul 1997 14:32:11 GMT
Jeff Smith wrote: > > My experience in floor performance is that even for spans greater than 14', > a L/480 deflection criteria is not desirable especially if there is not > sheet rock on the ceiling or any loads on the floor such as furniture to > dampen the vibration. A while back I specified 9-1/2" TJI/25 at 16" o.c. > for a 14' span which exceeds L/480 and in hindsight I felt it was a bit > bouncy. For custom homes in particular, this is an issue. An owner may > never know the difference unless it is brought to their attention, then it > will be considered unacceptable and they will do the old > "jumping-up-and-down-test" through out the house. Trus Joist will provide > performance crtiteria for their longer spans, because even if the strength > and deflection is well within the code and table limits, the floor will > vibrate. The TJI tables can be misinterpreted to allow an inexperieced > engineer to specify a poor performing, but legal floor for average to very > long spans. AISC has commentary that empirically limits vibration based on > the depth to span ratio for steel members. > Regards, > > Jeff Smith. S.E. I've been using the recommendations set forth in the paper "A Proposed Rule of Thumb for Controlling Annoying Vibrations in Residential Floors" by Frank E. Woeste with some success. The premise is that long span wood joist system peform best when the fundamantal frequency of vibration is held below 15 Hz. The formula developed considers the dead load as well as the EI of the joist. BTW, I believe copies of this paper were offered some time back on this list serve but I could be wrong. With regards to Trus Joist. They apparently are updating their design program to give better advice regarding control of deflections. In talking with them recently about a project, their engineer apparently had a pre release of the software which advises about relative performance levels for various "systems" including multiple blocking lines, gypsum board ceilings etc. I would encourage better communication about wood floor performance since we all have something to learn. Now if I can just convince TJI that windows 95 isn't the only operating system alive....... Barry H. Welliver Draper, UT wellive(--nospam--at)ibm.net --- Internet Message Header Follows --- Received: from server1.seaoc.org (bqe.com [126.96.36.199]) by host1.texramp.net (8.8.5/8.8.5) with SMTP id IAA11236 for <rlewis(--nospam--at)techteam.org>; Thu, 27 Feb 1997 08:50:02 -0600 (CST) Received: from out2.ibm.net by server1.seaoc.org (NTList 3.02.10) id ia004636; Thu, 27 Feb 1997 06:47:00 -0800 Received: (from uucp@localhost) by out2.ibm.net (8.6.9/8.6.9) id OAA25658 for <seaoc(--nospam--at)seaoc.org>; Thu, 27 Feb 1997 14:44:55 GMT Received: from slip129-37-226-66.ut.us.ibm.net(188.8.131.52) by out2.ibm.net via smap (V1.3mjr) id smaqB8DM2; Thu Feb 27 14:44:46 1997 Message-ID: <33158220.47B1(--nospam--at)ibm.net> Date: Thu, 27 Feb 1997 07:46:24 -0500 From: "Barry H. Welliver" <wellive(--nospam--at)ibm.net> Reply-To: seaoc(--nospam--at)seaoc.org X-Mailer: Mozilla 2.02E (OS/2; I) MIME-Version: 1.0 To: seaoc(--nospam--at)seaoc.org Subject: Re: floor deflections References: <199702252349.PAA05949(--nospam--at)mail1.sirius.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Error-To: seaoc-ad(--nospam--at)seaoc.org X-Loop: seaoc(--nospam--at)seaoc.org X-Info: [SEAOC] Owner: seaoc-ad(--nospam--at)seaoc.org X-POP3-Rcpt: seaoc-ad(--nospam--at)seaoc.org X-Sender: seaoc-ad(--nospam--at)seaoc.org Precedence: list X-ListMember: rlewis(--nospam--at)techteam.org [seaoc(--nospam--at)seaoc.org] __________________________________________________ Richard Lewis, P.E. Missionary TECH Team rlewis(--nospam--at)techteam.org The service mission like-minded Christian organizations may turn to for technical assistance and know-how.
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